IJV1

The use of ceiling mounted circulating fans to provide air movement for cooling in industrial premises and animal houses is particularly essential in warm, humid climates. Methods to substantially improve the efficiency of this approach are demonstrated in this paper. Fan laws are identified as one source of strategies for increasing energy-efficiency of fans. Industrial ceiling fans are used to demonstrate that using larger, slower, fans will not only improve energy efficiency but also reduce fan noise.

Climatisation and natural ventilation concepts are today, in most countries, considered to be an essential aspect of the building project. In fact they are utilised to guarantee summer thermal comfort and indoor air quality control. Also there are many other advantages including low energy use, reduction of noise levels and easy plant maintenance. In recent years the use of hybrid ventilation systems in office buildings has been developed. The achievement of thermal comfort conditions in buildings is an important aim in order to satisfy occupants.

A hybrid ventilation system combines both mechanical and natural ventilation modes. The natural ventilation mode, especially, causes some challenges for analysis tools since the varying nature of naturally driven flow means that transient calculations should be used to predict the flow fields. Analysis tools based on CFD have some advantages for detailed investigations since, in addition to evaluating the flow and temperature fields, it is possible to use CFD methods to calculate air exchange efficiency and other flow indices.

In the design of natural ventilation systems, there is a wide range of possibilities with regard to the selection of window type and the positioning of windows in the facade. Each window type has unique characteristics, which affect air flow and thermal comfort conditions in the occupied zone. A combination of various window types and faade locations in a room should be capable of improving thermal comfort and minimising draught risk.

This paper focuses on hybrid ventilation performance in an office building. It presents measurement results from the new headquarters of the company Bang & Olufsen, which served as one of the case study buildings in IEA ECBCS Annex 35. Ventilation and control strategy, as well as operational experience of the hybrid ventilation system is presented. Measurement results include long-term values of temperatures, CO2 and energy use for assisting fans and heating of ventilation air as well as electricity use for appliances.

This paper reports the results of computer simulations of a hybrid-ventilated building using ESP-r (Environmental Systems Performance for research). A new school building in Norway was used for this simulation study. The research attempted to verify the use of this model for the simulation of a real building utilising hybrid ventilation technologies. The simulations and their analysis focus on the buildings thermal and ventilation performance.

This paper describes the development of a simplified tool which should be used at the early design stage for predicting air ventilation rates in a building. The method is based on the assumption that the air flow rate may be calculated as a function of two independent parameters. The first, called effective pressure difference, takes into account the local weather data, surrounding terrain, and building typology. The second is the overall building permeability, and accounts for permeable components (geometry and permeability), including vents.

This study, which formed part of the Annex 35 Hybrid Ventilation in New and Retrofitted Office Buildings project, was completed at LEPTAB and supported by the French Research Ministry and the ADEME (Agence De lEnvironnement et de la Matrise de lEnergie). It consisted of modelling a typical classroom and comparing different control strategies to estimate the performance of a hybrid ventilation system for different climates.

The demand for buildings with high quality indoor environments is growing, especially in developing countries, where more and more energy will be consumed in the near future. Air flow pattern, air temperature and humidity are among the main parameters that contribute to indoor thermal comfort. Care must be taken to design the most energy-efficient air distribution system that provides comfort for the occupants. To achieve this it is very helpful to know the air flow patterns and the temperature and humidity field in a building at the design stage.

The basic mechanism for natural ventilation in a building involves air flowing through purpose-made ventilator openings. These ventilators must be carefully designed as natural ventilation driving forces are weak compared to the dynamic forces created by mechanical systems. This paper describes a series of experimental parametric studies that investigated how components within a ventilator (in this case louvers and wire mesh screens) interacted. Air flow measurements through the individual louver and mesh components were compared to the air flow through mesh / louver combinations.